Multiple-phase power converter having current sharing and high frequency filtering

Abstract

A multiple-phase power converter comprises a first inductor and a second inductor having respective input terminals and respective output terminals. The output terminals are connected together to provide a common output terminal of the multiple-phase power converter. At least a first switch circuit is connected to the input terminal of the first inductor and a second switch circuit is connected to the input terminal of the second inductor. At least one voltage source is coupled to the first and second switch circuits. A controller is adapted to control operations of the first and second switch circuits to alternately connect the input terminals of the respective inductors to the respective voltage source and ground. The controller includes an error amplifier providing a signal corresponding to a difference between respective voltage waveforms across the first and second inductors. The error amplifier includes a feedback loop providing filtering of at least one of the voltage waveforms. The controller adjusts duty cycles applied to the first and second switch circuits responsive to the signal to achieve substantially equal current in the respective inductors.

What is claimed is:  
     
         1 . A multiple-phase power converter, comprising: 
 at least a first inductor and a second inductor having respective input terminals and respective output terminals, said output terminals connected together;    at least a first switch circuit connected to said input terminal of said first inductor and a second switch circuit connected to said input terminal of said second inductor;    at least one voltage source coupled to said first and second switch circuits; and    a controller adapted to control operations of said first and second switch circuits to alternately connect said input terminals of the respective inductors to said respective voltage source and ground, said controller including an error amplifier providing a signal corresponding to a difference between respective voltage waveforms across the first and second inductors, said error amplifier including a feedback loop providing filtering of at least one of said voltage waveforms, said controller adjusting duty cycles applied to said first and second switch circuits responsive to said signal to achieve substantially equal current in the respective inductors.    
     
     
         2 . The multiple-phase power converter of  claim 1 , wherein said feedback loop further provides gain and phase adjustment of said signal.  
     
     
         3 . The multiple-phase power converter of  claim 1 , wherein said first and second switch circuits each further comprises a high-side switch coupled to said at least one voltage source and a low-side switch coupled to ground.  
     
     
         4 . The multiple-phase power converter of  claim 1 , wherein said feedback loop further comprises at least a capacitor connected between an output terminal of said error amplifier and an inverting input terminal of said error amplifier.  
     
     
         5 . The multiple-phase power converter of  claim 1 , wherein said controller further comprises an integrated circuit with said error amplifier included therein, said integrated circuit including external pins adapted for connection of said feedback loop between an output terminal of said error amplifier and at least one input terminal of said error amplifier.  
     
     
         6 . The multiple-phase power converter of  claim 1 , wherein said at least one voltage source further comprises a first voltage source connected to said first switch circuit and a second voltage source connected to said second switch circuit.  
     
     
         7 . The multiple-phase power converter of  claim 6 , wherein said first voltage source and said second voltage source each have different voltage levels.  
     
     
         8 . The multiple-phase power converter of  claim 6 , wherein said first voltage source and said second voltage source each have the same voltage level.  
     
     
         9 . A multiple-phase power converter with forced current sharing, comprising: 
 at least a first inductor and a second inductor having respective input terminals and respective output terminals, said output terminals connected together;    at least a first switch circuit connected to said input terminal of said first inductor and a second switch circuit connected to said input terminal of said second inductor;    at least one voltage source coupled to said first and second switch circuits;    means for converting voltage waveforms at respective ones of said input terminals into respective sensed voltages;    means for comparing said sensed voltages to provide a current sharing signal;    means for active filtering said current sharing signal; and    means for adjusting duty cycles of said respective voltage waveforms responsive to said current sharing signal to achieve equal sensed voltages.    
     
     
         10 . The multiple-phase power converter of  claim 9 , wherein said voltage converting means further comprises sensing resistors coupled to respective ones of said input terminals.  
     
     
         11 . The multiple-phase power converter of  claim 10 , wherein said comparing means further comprises an error amplifier having input terminals connected to respective ones of said sensing resistors.  
     
     
         12 . The multiple-phase power converter of  claim 11 , wherein said active filtering means further a feedback loop connected between an output terminal of said error amplifier and one of said input terminals of said error amplifier.  
     
     
         13 . The multiple-phase power converter of  claim 9 , wherein said first and second switch circuits each further comprises a high-side switch coupled to said at least one voltage source and a low-side switch coupled to ground.  
     
     
         14 . The multiple-phase power converter of  claim 9 , wherein said at least one voltage source further comprises a first voltage source connected to said first switch circuit and a second voltage source connected to said second switch circuit.  
     
     
         15 . The multiple-phase power converter of  claim 14 , wherein said first voltage source and said second voltage source each have different voltage levels.  
     
     
         16 . The multiple-phase power converter of  claim 14 , wherein said first voltage source and said second voltage source each have the same voltage level.  
     
     
         17 . In a multiple-phase power converter comprising at least a first inductor and a second inductor having respective input terminals and respective output terminals, said output terminals connected together, at least a first switch circuit connected to said input terminal of said first inductor and a second switch circuit connected to said input terminal of said second inductor, and at least one voltage source coupled to said first and second switch circuits, a method for forcing current sharing comprises the steps of: 
 sensing voltage waveforms at respective input terminals of said first and second inductors;    applying said sensed voltages to respective input terminals of an error amplifier;    filtering high frequency components of at least one of said voltage waveforms using a feedback loop of said error amplifier;    generating a current share signal corresponding to differences between said sensed voltages; and    adjusting duty cycles applied to said first and second switch circuits responsive to said current share signal.    
     
     
         18 . The method of  claim 17 , further comprising adjusting at least one of gain and phase of said current share signal.  
     
     
         19 . The method of  claim 17 , wherein said error amplifier is included within an integrated circuit adapted to control said multiple-phase power converter, and wherein said filtering step further comprises connecting said feedback loop to respective externally accessible pins of said integrated circuit corresponding to an output terminal of said error amplifier and at least one input terminal of said error amplifier.  
     
     
         20 . The method of  claim 19 , wherein said filtering step further comprises connecting a capacitor between said respective externally accessible pins.